What Are The Precautionary Steps Taken For Measuring With A Vernier Caliper?

A Vernier Caliper is used for more precise measurements. You’ll come across this device in high school practical lessons where you’ll have to measure lengths, diameters, etc. correct to two decimal points.

Several precautionary measures need to be implemented to avoid errors in measurement with a Vernier caliper. Some of these errors are unavoidable and mainly arise due to certain environmental conditions and presence of errors in the system. But some of these also arise from human carelessness, lack of knowledge and misjudgment resulting greater deviations.

We should try to decrease the human errors as much as possible while measuring with a Vernier Caliper. Below we have enlisted a few precautionary measures that you should implement while measuring with the help of a Caliper.

For Analog Vernier Calipers

Parallax error

This is the most common form of error associated with measuring devices. The error arises when the measurement is done at an angle. When the object’s observed at an angle, it makes the object appear at a moderately different position than the place where it actually is. Hence, naturally, it leads to a wrong reading on the scale.

To eliminate parallax error, it’s necessary for the observer to place his/her directly above the measuring scale keeping a straight line as much as possible. This practice needs to be done when the observer’s involved in taking the MSR (Main Scale reading) and the Vernier Coincidence.

Maintaining the same unit system

All measurements need to be done in the same unit system. It can be the CGS system (centimeter, gram, second) or the MKS system (meter, kilogram, second) but care should be taken that the similarity is maintained.

Avoiding excessive force on the Vernier jaws

The object that needs to be measured must be gripped gently within the jaws. Excessive force on the jaws must be avoided. This point is extremely significant in the case of objects that are readily deformable such as wires. If you are involved in any measurements with a Vernier Caliper and wire, do keep this point in your mind while performing the measurements.

No Zero error

In simpler words, zero error is defined to be the incorrect reading that you get on an instrument measuring something that should read 0 (zero).

Before you take any measurement with the Calipers, ensure the fact that the Caliper is devoid of any error. You can check this by bringing together the Caliper jaws in contact with one another. You’ll have to make sure that at this position the zero mark on the Vernier scale aligns with that of the main scale. If the alignment’s perfect, your scale is devoid of zero error, and you can perform accurate measurements with the same instrument. If it’s not, your scale has zero error, and necessary corrections need to be done. There are two types of zero error- positive zero error and negative zero error. For more details, you can refer to this article.

Surface of the object should be clean

The surface of the object that is to be measured must be cleaned appropriately with a cloth soaked in oil for precise measurement. Do not forget to dry the object after you have cleaned it thoroughly with the cloth. The cover of the instrument should also be kept clean to prevent the accumulation of grime and rust which will surely result in inaccurate measurements. The Vernier jaws should also be cleaned in the same way mentioned above.

For Digital Vernier Calipers

Check the presence of zero error on your device. Bring the jaws close to one another such that one is in contact with the other and then switch the device on. The reading should read zero at this point. If it doesn’t read zero, your device has a zero error.

This point is pretty obvious. Make sure that your device is in a good working condition by checking on the accessory parts such as the LCD, the buttons, etc. by simply moving the slider with the device switched on.

Many errors are unavoidable and depend greatly on the circumstances. It’s true that such errors cannot be removed. But certain errors are within our control and we can remove them by careful observation and patience. The precautionary measures highlighted above can definitely bring the errors under control at least to a certain level.

Sudipto Das

Sudipto writes technical and educational content periodically for wizert.com and backs it up with extensive research and relevant examples. He's an avid reader and a tech enthusiast at the same time with a little bit of “Arsenal Football Club” thrown in as well. He's got a B.Tech in Electronics and Instrumentation.
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